116 lines
2.4 KiB
C
116 lines
2.4 KiB
C
/*-
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* Copyright (c) 2004,2008 Oracle. All rights reserved.
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*
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* http://www.apache.org/licenses/LICENSE-2.0.txt
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*
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* authors: George Schlossnagle <george@omniti.com>
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*/
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extern "C"
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{
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#include <sys/types.h>
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#include <sys/ipc.h>
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#include <sys/sem.h>
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#include <sys/stat.h>
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#include <unistd.h>
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#include "config.h"
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#include "sem_utils.h"
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#include <errno.h>
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}
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extern int errno;
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#if HAVE_SEMUN
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/* we have semun, no need to define */
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#else
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union semun {
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int val; /* value for SETVAL */
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struct semid_ds *buf; /* buffer for IPC_STAT, IPC_SET */
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unsigned short *array; /* array for GETALL, SETALL */
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/* Linux specific part: */
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struct seminfo *__buf; /* buffer for IPC_INFO */
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};
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#endif
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#ifndef SEM_R
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# define SEM_R 0444
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#endif
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#ifndef SEM_A
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# define SEM_A 0222
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#endif
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int md4_sem_create(int semnum, unsigned short *start)
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{
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int semid;
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int perms = 0777;
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union semun arg;
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key_t key = 12345;
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int count = 0;
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while((semid = semget(key, semnum, IPC_CREAT | IPC_EXCL | perms)) == -1) {
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if(count++ > 2) {
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return -1;
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}
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if (errno == EEXIST) {
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semid = semget(key, 1, perms);
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md4_sem_destroy(semid);
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}
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}
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arg.array = start;
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if(semctl(semid, 0, SETALL, arg) < 0) {
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/* destroy (FIXME) and return */
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md4_sem_destroy(semid);
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return -1;
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}
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return semid;
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}
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void md4_sem_destroy(int semid)
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{
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union semun dummy;
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/* semid should always be 0, this clobbers the whole set */
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semctl(semid, 0, IPC_RMID, dummy);
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}
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void md4_sem_lock(int semid, int semnum)
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{
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struct sembuf sops;
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sops.sem_num = semnum;
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sops.sem_op = -1;
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sops.sem_flg = SEM_UNDO;
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semop(semid, &sops, 1);
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}
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void md4_sem_unlock(int semid, int semnum)
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{
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struct sembuf sops;
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sops.sem_num = semnum;
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sops.sem_op = 1;
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sops.sem_flg = SEM_UNDO;
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semop(semid, &sops, 1);
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}
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void md4_sem_wait_for_zero(int semid, int semnum)
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{
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struct sembuf sops;
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sops.sem_num = semnum;
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sops.sem_op = 0;
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sops.sem_flg = SEM_UNDO;
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semop(semid, &sops, 1);
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}
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void md4_sem_set(int semid, int semnum, int value)
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{
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union semun arg;
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arg.val = value;
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semctl(semid, semnum, SETALL, arg);
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}
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int md4_sem_get(int semid, int semnum)
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{
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union semun arg;
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return semctl(semid, 0, GETVAL, arg);
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}
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/* vim: set ts=4 sts=4 expandtab bs=2 ai : */
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